Challenging Popular Belief, Mosquito Larvae Breathe Underwater.

Immature mosquitoes are thought to breathe only atmospheric air through their siphons despite reports of prolonged submerged survival. We studied the survival of last-instar larvae of Aedes aegypti fully submerged at different temperatures and measured the oxygen consumption from air and water-dissolved larvae and pupae of this species under different conditions. Larvae survived much longer than expected, reaching 50% mortality only after 58, 10, and 5 days at 15°, 25°, and 35 °C, respectively. Larval to pupa molt was only observed in larvae with access to air, whereas individuals kept submerged never molted. Although most of the oxygen was obtained from the air, larvae obtained 12.72% of their oxygen from the water, while pupae took only 5.32%. In both media, temperature affected the respiration rate of the larvae, with relatively close Q10 values (1.56 and 1.83 for water and air, respectively). A similar pattern of O2 consumption was observed in Ae. albopictus, whose larvae obtained 12.14% of their oxygen from the water. The detailed quantification of oxygen consumption by mosquito larvae showed that water-dissolved oxygen is not negligible and physiologically relevant, challenging the idea that mosquito larvae only breathe atmospheric oxygen.

A rapid method for screening mosquito repellents on Anopheles pseudopunctipennis and Aedes aegypti.

One of the main vectors for malaria in Latin America is Anopheles pseudopunctipennis (Theobald), whereas Aedes aegypti (L.) is the primary vector of dengue, yellow fever, Zika and chikungunya viruses. The use of repellents is recommended as a personal protection method against these mosquitoes. However there are very few studies evaluating the effect of repellents on An. pseudopunctipennis. The use of a Petri dish to study repellence has been applied by several authors on flies, cockroaches, kissing bugs and mosquitoes, being a valuable technique for species that are difficult to breed under laboratory conditions, such as An. pseudopunctipennis. In the present study, we evaluated the repellence of the essential oil of the Eucalyptus nitens (Shining gum), its main component (1,8-cineole) and the commercial repellent DEET on An. pseudopunctipennis and Ae. aegypti adult females using the plaque repellency method coupled to EthoVision XT10.1 video-tracking software. Repellent effect and locomotor activity were studied through a repellence index (RI) together with an axis constructed from the behavioural variables obtained using the tracking software. DEET repellent effect was observed at 0.01 mg/mL for Ae. aegypti and 0.01 and 0.1 mg/mL for An. pseudopunctipennis. In addition, the essential oil showed significant repellence at 1 and 10 mg/mL for Ae. aegypti, and 1, 5, 10 and 25 mg/mL for An. pseudopunctipennis. Neither of these species were repelled at any concentration of 1,8-cineole. This is the first study that evaluates these compounds on An. pseudopunctipennis females and quantifies their effects on the activity of both species.

Evolution of the strikingly diverse submandibular muscles in Anura.

The most ventral muscles of the head (the mm. submentalis, intermandibularis, and interhyoideus) provide support to the gular region and lift the buccal floor during ventilation and feeding. These muscles show limited variation in most gnathostomes, but in Anura they exhibit a surprising diversity. The few studies that have explored this character system highlighted its potential as a source of phylogenetic information. In this paper we explored the diversity of this character system studying specimens of 567 anuran species and reviewing published data to cover a total of 1321 species, belonging to 53 of the 54 currently recognized anuran families, as well as caudates and caecilians. We defined 27 discrete characters including the number of muscle bellies, supplementary layers, hypertrophy and diversity of elastic fibres, and pigmentation, among others, and optimized them on a comprehensive phylogenetic hypothesis. We recognized 223 unambiguously optimized synapomorphies for numerous clades on different scales, including three for Anura and many for suprafamiliar clades with poor phenotypic support. Finally, we discussed the evolution of this highly diverse character system, including homology, development, and its functional role in vocalization and feeding. Interestingly, the striking levels of variation in some structures contrast with the amount of phylogenetic inertia, allowing us to recognize several general patterns. Supplementary elements of the m. intermandibularis evolved first as broad layers occuring in more than half of extant anuran species and then concentrated forming discreet bellies in several clades. The anterior portion of the gular region is not sexually dimorphic, and is likely related to ventilation and tongue protraction. Conversely, the diversity of the m. interhyoideus is strongly linked to vocal sacs, which are present only in adult males, suggesting the presence of two independent modules.

A closer look at pupil diversity and evolution in frogs and toads.

The eyes of frogs and toads (Anura) are among their most fascinating features. Although several pupil shapes have been described, the diversity, evolution, and functional role of the pupil in anurans have received little attention. Studying photographs of more than 3200 species, we surveyed pupil diversity, described their morphological variation, tested correlation with adult habits and diel activity, and discuss major evolutionary patterns considering iris anatomy and visual ecology. Our results indicate that the pupil in anurans is a highly plastic structure, with seven main pupil shapes that evolved at least 116 times during the history of the group. We found no significant correlation between pupil shape, adult habits, and diel activity, with the exception of the circular pupil and aquatic habits. The vertical pupil arose at least in the most-recent common ancestor of Anura + Caudata, and this morphology is present in most early-diverging anuran clades. Subsequently, a horizontal pupil, a very uncommon shape in vertebrates, evolved in most neobatrachian frogs. This shape evolved into most other known pupil shapes, but it persisted in a large number of species with diverse life histories, habits, and diel activity patterns, demonstrating a remarkable functional and ecological versatility.

Machine-learning model led design to experimentally test species thermal limits: The case of kissing bugs (Triatominae).

Species Distribution Modelling (SDM) determines habitat suitability of a species across geographic areas using macro-climatic variables; however, micro-habitats can buffer or exacerbate the influence of macro-climatic variables, requiring links between physiology and species persistence. Experimental approaches linking species physiology to micro-climate are complex, time consuming and expensive. E.g., what combination of exposure time and temperature is important for a species thermal tolerance is difficult to judge a priori. We tackled this problem using an active learning approach that utilized machine learning methods to guide thermal tolerance experimental design for three kissing-bug species: Triatoma infestans, Rhodnius prolixus, and Panstrongylus megistus (Hemiptera: Reduviidae: Triatominae), vectors of the parasite causing Chagas disease. As with other pathogen vectors, triatomines are well known to utilize micro-habitats and the associated shift in microclimate to enhance survival. Using a limited literature-collected dataset, our approach showed that temperature followed by exposure time were the strongest predictors of mortality; species played a minor role, and life stage was the least important. Further, we identified complex but biologically plausible nonlinear interactions between temperature and exposure time in shaping mortality, together setting the potential thermal limits of triatomines. The results from this data led to the design of new experiments with laboratory results that produced novel insights of the effects of temperature and exposure for the triatomines. These results, in turn, can be used to better model micro-climatic envelope for the species. Here we demonstrate the power of an active learning approach to explore experimental space to design laboratory studies testing species thermal limits. Our analytical pipeline can be easily adapted to other systems and we provide code to allow practitioners to perform similar analyses. Not only does our approach have the potential to save time and money: it can also increase our understanding of the links between species physiology and climate, a topic of increasing ecological importance.

Surfactantless Emulsions Containing Eugenol for Imidacloprid Solubilization: Physicochemical Characterization and Toxicity against Insecticide-Resistant Cimex lectularius.

Synthetic insecticides have been used for a long time as one of the most effective tools for insect pest control. However, the re-emergence of insect pests and their fast development of resistance, as has occurred for pyrethroid-resistant bed bugs Cimex lectularius L., make it necessary to develop new and safe strategies for effective pest control. This has fostered the research on new eco-sustainable formulations based on essential oils, which allows reducing the impact associated with the intensive use of synthetic insecticides on the environment and their effects on human health. This research explores the stability of water/eugenol/ethanol surfactantless emulsions loaded with imidacloprid (0.003 wt%), and their toxicity against a resistant bed bug strain. The results have shown that these emulsions enable the solubilization of a poorly water-soluble drug, such as the imidacloprid, without any significant modification of their stability. Furthermore, the application of the obtained formulations against the pyrethroid-resistant bed bug results in mortality in the 50-85% range upon topical and spray applications, with the increase of the eugenol content enhancing the effectiveness of the formulations. It may be expected that the ternary water/eugenol/ethanol mixtures could be further developed in the preparation of ready to use formulations, enabling the dispersion of insecticides for pest control.

High effectiveness of an adulticide-larvicide formulation for field control of sandflies (Diptera: Psychodidae) in the city of Clorinda, Argentina.

In Argentina, Leishmania infantum (syn. L. chagasi) is the etiologic agent of human visceral leishmaniosis (HVL), and Lutzomyia longipalpis (Diptera: Psychodidae: Phlebotominae) is the main vector. The objective of this study was to evaluate the effectiveness and residual effect of two commercial insecticide formulations, one with permethrin and pyriproxyfen as active ingredients (Dragon Max®) and the other with only permethrin (Flop®) for the control of sandflies. Both formulations were applied in chicken coops and other surroundings structures of the peridomicile of urban houses in Clorinda, Formosa (Argentina). Entomological monitoring was carried out weekly for 44 weeks after the intervention. The results showed great effectiveness and residual effect up to 21 weeks post-intervention for Dragon Max®. This result could be explained by the excellent larvicidal activity of the Insect Growth Regulator (IGR) pyriproxyfen against the immature forms of phlebotomines and by the delay on the restoration of the natural threshold of the vector population in treated sites.

Effects of Temephos, Permethrin, and Eucalyptus nitens Essential Oil on Survival and Swimming Behavior of Aedes aegypti and Anopheles pseudopunctipennis (Diptera: Culicidae) Larvae.

An essential strategy to deal with mosquito-borne diseases is the control of larvae in their development sites. The mosquitoes Anopheles pseudopunctipennis (Theobald) (Diptera: Culicidae), a malaria vector, and Aedes aegypti (L.) (Diptera: Culicidae), vector of dengue, Zika, yellow fever, and chikungunya viruses, breed in very different habitats. Insecticide treatments of mosquito larvae focus mainly on their lethal effects. However, insecticide degradation or the poor dosage of larvicides will invariably lead to the sublethal exposure of a target (and nontarget) species, the nonlethal effects of these compounds may have important effects on vital insect activities, and therefore their evaluation is necessary. In this study, we assessed the survival and swimming behavior of larvae of Ae. aegypti and An. pseudopunctipennis exposed to increasing concentrations of three larvicides. We found that Ae. aegypti, was more sensitive to the larvicides than An. pseudopunctipennis, we also observed an overall decrease in the movement of those larvae of both species, which survive the treatments. This decrease might have ecological relevance in their natural habitats, increasing the chance to be predated and decreasing their ability to obtain food. Finally, this information will be valuable to assist authorities to make decisions in the implementation of further control programs.

Targeting Beta-Amyloid at the CSF: A New Therapeutic Strategy in Alzheimer's Disease.

Although immunotherapies against the amyloid-ß (Aß) peptide tried so date failed to prove sufficient clinical benefit, Aß still remains the main target in Alzheimer's disease (AD). This article aims to show the rationale of a new therapeutic strategy: clearing Aß from the CSF continuously (the "CSF-sink" therapeutic strategy). First, we describe the physiologic mechanisms of Aß clearance and the resulting AD pathology when these mechanisms are altered. Then, we review the experiences with peripheral Aß-immunotherapy and discuss the related hypothesis of the mechanism of action of "peripheral sink." We also present Aß-immunotherapies acting on the CNS directly. Finally, we introduce alternative methods of removing Aß including the "CSF-sink" therapeutic strategy. As soluble peptides are in constant equilibrium between the ISF and the CSF, altering the levels of Aß oligomers in the CSF would also alter the levels of such proteins in the brain parenchyma. We conclude that interventions based in a "CSF-sink" of Aß will probably produce a steady clearance of Aß in the ISF and therefore it may represent a new therapeutic strategy in AD.

The vocal sac of Hylodidae (Amphibia, Anura): Phylogenetic and functional implications of a unique morphology.

Anuran vocal sacs are elastic chambers that recycle exhaled air during vocalizations and are present in males of most species of frogs. Most knowledge of the diversity of vocal sacs relates to external morphology; detailed information on internal anatomy is available for few groups of frogs. Frogs of the family Hylodidae, which is endemic to the Atlantic Forest of Brazil and adjacent Argentina and Paraguay, have three patterns of vocal sac morphology-that is, single, subgular; paired, lateral; and absent. The submandibular musculature and structure of the vocal sac mucosa (the internal wall of the vocal sac) of exemplar species of this family and relatives were studied. In contrast to previous accounts, we found that all species of Crossodactylus and Hylodes possess paired, lateral vocal sacs, with the internal mucosa of each sac being separate from the contralateral one. Unlike all other frogs for which data are available, the mucosa of the vocal sacs in these genera is not supported externally by the mm. intermandibularis and interhyoideus. Rather, the vocal sac mucosa projects through the musculature and is free in the submandibular lymphatic sac. The presence of paired, lateral vocal sacs, the internal separation of the sac mucosae, and their projection through the m. interhyoideus are synapomorphies of the family. Furthermore, the specific configuration of the m. interhyoideus allows asymmetric inflation of paired vocal sacs, a feature only reported in species of these diurnal, stream-dwelling frogs.

A Video-Tracking Analysis-Based Behavioral Assay for Larvae of Anopheles pseudopunctipennis and Aedes aegypti (Diptera: Culicidae).

Aedes aegypti (L.) is the primary vector of dengue, yellow fever, Zika, and chikungunya viruses, whereas Anopheles pseudopunctipennis (Theobald) is the principal vector for malaria in Latin America. The larval stage of these mosquitoes occurs in very different development habitats, and the study of their respective behaviors could give us valuable information to improve larval control. The aim of this study was to set up a bioassay to study basic larval behaviors using a video-tracking software. Larvae of An. pseudopunctipennis came from two localities in Salta Province, Argentina, while Ae. aegypti larvae were of the Rockefeller laboratory strain. Behaviors of individual fourth-instar larvae were documented in an experimental petri dish arena using EthoVision XT10.1 video-tracking software. The overall level of movement of larval An. pseudopunctipennis was lower than that for Ae. aegypti, and, while moving, larval An. pseudopunctipennis spent significantly more time swimming near the wall of the arena (thigmotaxis). This is the first study that analyzes the behavior of An. pseudopunctipennis larvae. The experimental system described here may be useful for future studies on the effect of physiological, toxicological, and chemosensory stimuli on larval behaviors.

Repellent and Larvicidal Activity of the Essential Oil From Eucalyptus nitens Against Aedes aegypti and Aedes albopictus (Diptera: Culicidae).

Dengue, chikungunya, and yellow fever are important vector-borne diseases transmitted by female mosquitoes when they feed on humans. The use of repellents based on natural products is an alternative for personal protection against these diseases. Application of chemicals with larvicidal activity is another strategy for controlling the mosquito population. The repellent and larvicidal activities of the essential oil from Eucalyptus nitens were tested against Aedes aegypti and Aedes albopictus, the main vectors of these arboviruses. The essential oil was extracted by hydrodistillation and then analyzed by gas chromatography-mass spectrometry. The main components of Eucalyptus nitens essential oil were found to be terpenes such as 1,8-cineole and p-cymene, followed by ß-triketones and alkyl esters. The repellent activity of the essential oil against both species was significantly higher when compared with the main component, 1,8-cineole, alone. These results indicate that the repellent effect of E. nitens is not due only to the main component, 1,8-cineole, but also that other compounds may be responsible. Aedes aegypti was found to be more tolerant to the essential oil larvicidal effects than Ae. albopictus (Ae. aegypti LC50 = 52.83 ppm, Ae. albopictus LC 50 = 28.19 ppm). The repellent and larvicidal activity could be associated to the presence of cyclic ß-triketones such as flavesone, leptospermone, and isoleptospermone.

Incidence and characteristics of myelodysplastic syndromes in Ourense (Spain) between 1994-1998.

The very few reference epidemiological studies on myelodysplastic syndromes (MDS) have been carried out in Europe: Germany, France, UK and Sweden. We present the first Spanish study on the incidence and characteristics of MDS. The incidence rates, distribution by FAB subtypes, sex and age groups are within the ranges established by the reference studies with minimal differences which we point out and attempt to explain.

Síndrome de Muir-Torre / Muir-Torre's Syndrome

El síndrome de Muir-Torre es una genodermatosis en la que una o múltiples neoplasias internas están asociadas a adenomas, epiteliomas o carcinomas sebáceos. Presentamos el caso de un paciente varón de 60 años que acude a consulta por varias neoplasias en área facial, entre las cuales figura un adenoma sebáceo y varios queratoacantomas. Tras este hallazgo, en una exploración dirigida a buscar neoplasias internas asociadas, se detectó un adeno-carcinoma de colon. Tiene historia familiar de neoplasias gastrointestinales y ginecológicas. Las lesiones cutáneas pueden ser la primera expresión del síndrome y por tanto deben ser conocidas para detectar tempranamente un proceso neoplásico asociado (AU)